Mr Trump, the Republican nominee, said he watched Mrs Clinton's speech the night before in Philadelphia.

He criticised her speech as being "full of cliches" and full of false claims against him.

Mr Trump also bragged about TV ratings that indicated that more people watched his acceptance speech that Mrs Clinton's speech. The Democratic convention, however, had more overall viewers during the four nights.

He said that he thought Chelsea Clinton did very well and noted that she is friends with his daughter Ivanka. He joked that he wished they were not friends "because it would be a lot easier!"

Mr Trump also complained that the fire marshal in Colorado Springs would not let more people into his event.

Mrs Clinton had cast herself as a unifier for divided times, an experienced leader steeled for a volatile world - and aggressively Mr Trump's ability to do the same.

"Imagine him in the Oval Office facing a real crisis," the former US secretary of state and first lady said, as she accepted the Democratic nomination for president early on Friday.

"A man you can bait with a tweet is not a man we can trust with nuclear weapons."

Mrs Clinton took the stage to roaring applause from flag-waving delegates on the final night of the Democratic convention in Philadelphia, relishing her nomination as the first woman to lead a major US political party.

But her real audience was the millions of voters watching at home, many of whom may welcome her experience, but question her character.

She acknowledged those concerns briefly, saying: "I get it that some people just don't know what to make of me." But her primary focus was persuading Americans to not be seduced by Republican presidential candidate Mr Trump's vague promises to restore economic security and fend off threats from abroad.

Mrs Clinton said the US needed a leader who would work with allies to keep America safe.

The presidential election presented a stark choice on national security, she said, with the US facing "determined enemies that must be defeated".

She said people wanted "steady leadership", vowing to stand by Nato allies against any Russian threats.

And she pledged to defeat the Islamic State group with air strikes and support for local ground forces, while authorising a "surge" in intelligence to prevent terrorist attacks.

Former Reagan administration official Doug Elmets announced he was casting his first vote for a Democrat in November and urged other Republicans who "believe loyalty to our country is more important than loyalty to party" to do the same.

Following reports Russia hacked Democratic Party emails, Mr Trump said he would like to see Moscow find the thousands of emails Mrs Clinton deleted from the account she used as secretary of state.

Hours later, he told Fox News he was being "sarcastic", although shortly after his remarks on Wednesday, he tweeted that Russia should share the emails with the FBI.

Mr Trump attacked Mrs Clinton for not saying the words "radical Islam" in her speech.

"Our way of life is under threat by Radical Islam and Hillary Clinton cannot even bring herself to say the words," he said in a series of tweets.

Neither Mrs Clinton nor US president Barack Obama uses the phrase "radical Islam" because they say it is misleading, pointing out that the ideology motivating terrorists does not reflect true Islam.

But Republicans argue that the failure to use the label has hampered the fight against terror.

In her speech, Mrs Clinton said she would work to fight the radicalisation of young people in the US and abroad.